The phenotypes are similar to published results on the bone morphogenetic proteins (Bmps), such as haploinsufficiency of Bmp2 causing exencephaly comparable to Fig. 7A, [53], and compound heterozygous mutants for Bmp2 and Bmp4 showing unilateral microphthalmia similar to Fig. 6–7, [54]. Here, BMP4 is linked to microphthalmia.